Bipolar Molecular Torque Wrench Modulates the Stacking of Two-Dimensional Metal-Organic Framework Nanosheets.

The precise modulation of nanosheet stacking modes introduces unforeseen properties and creates momentous applications but remains a challenge. Herein, we proposed a strategy using bipolar molecules as torque wrenches to control the stacking modes of 2-D Zr-1,3,5-(4-carboxylphenyl)-benzene metal-organic framework (2-D Zr-BTB MOF) nanosheets. The bipolar phenyl-alkanes, phenylmethane (P-C1) and phenyl ethane (P-C2), predominantly instigated the rotational stacking of Zr-BTB-P-C1 and Zr-BTB-P-C2, displaying a wide angular distribution. This included Zr-BTB-P-C1 orientations at 0, 12, 18, and 24° and Zr-BTB-P-C2 orientations at 0, 6, 12, 15, 24, and 30°. With reduced polarity, phenyl propane (P-C3) and phenyl pentane (P-C5) introduced steric hindrance and facilitated alkyl hydrophobic interactions with the nanosheets, primarily resulting in the modulation of eclipsed stacking for Zr-BTB-P-C3 (64.8%) and Zr-BTB-P-C5 (93.3%) nanosheets. The precise angle distributions of four Zr-BTB-P species were in agreement with theoretical calculations. The alkyl induction mechanism was confirmed by the sequential guest replacement and 2-D 13C-1H heteronuclear correlation (HETCOR). In addition, at the single-particle level, we first observed that rotational stacked pores exhibited similar desorption rates for xylene isomers, while eclipsed stacked pores showed significant discrepancy for xylenes. Moreover, the eclipsed nanosheets as stationary phases exhibited high resolution, selectivity, repeatability, and durability for isomer separation. The universality was proven by another series of bipolar acetate-alkanes. This bipolar molecular torque wrench strategy provides an opportunity to precisely control the stacking modes of porous nanosheets.

Increasing Mass Transfer Resistance of MOFs as a Reverse Tuning Strategy to Achieve High-Resolution Gas Chromatographic Separation.

In separation science, precise control and regulation of the MOF stationary phase are crucial for achieving a high separation performance. We supposed that increasing the mass transfer resistance of MOFs with excessive porosity to achieve a moderate mass transfer resistance of the analytes is the key to conducting the MOF stationary phase with a high resolution. Three-dimensional UiO-67 (UiO-67-3D) and two-dimensional UiO-67 (UiO-67-2D) were chosen to validate this strategy. Compared with UiO-67-3D with overfast mass transfer and low retention, the reduced porosity of UiO-67-2D increased the mass transfer resistance of analytes in reverse, resulting in improved separation performance. Kinetic diffusion experiments were conducted to verify the difference in mass transfer resistance of the analytes between UiO-67-3D and UiO-67-2D. In addition, the optimization of the UiO-67-2D thickness for separation revealed that a moderate diffusion length of the analytes is more advantageous in achieving the equilibrium of absorption and desorption.

Effect of mindfulness-based stress reduction in patients with acute myocardial infarction after successful primary percutaneous coronary intervention: a retrospective study.

OBJECTIVE: This study aimed to examine the effects of mindfulness-based stress reduction (MBSR) in patients with acute myocardial infarction (AMI) after primary percutaneous coronary intervention (PPCI). METHODS: A retrospective study was conducted with data collected from AMI patients who underwent successful PPCI. The study included 61 cases that received 8-week MBSR intervention (MBSR group) and 61 cases that received weekly health education (control group) over the same period. Outcome measures, including hemodynamic parameters, psychosocial characteristics [Hospital Anxiety and Depression Scale (HADS), Perceived Stress Scale (PSS), Perceived Social Support Scale (PSSS)], health-related quality of life [HRQoL, 7-item Seattle Angina Questionnaire (SAQ-7)], and major adverse cardiovascular events (MACE), were assessed at baseline (T1), post-intervention (T2), 1 month after the post-intervention (T3) and 3 months after the post-intervention (T4). RESULTS: Compared to the control group, the MBSR group showed improvements in blood pressure, specifically in systolic blood pressure (SBP) at T4, and diastolic blood pressure (DBP) at T3 and T4, and mean arterial blood pressure (MABP) at T3 and T4. Additionally, the MBSR group had lower scores of anxiety and perceived stress (HADS, PSS) and higher scores of perceived social support (PSSS) after the intervention. Furthermore, the MBSR group had higher scores on the SAQ-7 at all measurement points. The control group had a significantly higher total MACE rate compared to the MBSR group (26.23% vs. 9.84%). CONCLUSIONS: This study provides support for the potential benefits of MBSR as an adjunctive treatment for AMI patients undergoing PPCI.

Enhancing Separation Abilities of "Low-Performance" Metal-Organic Framework Stationary Phases through Size Control.

Peak broadening and peak tailing are common but rebarbative phenomena that always occur when using metal-organic frameworks (MOFs) as stationary phases. These phenomena result in diverse "low-performance" MOF stationary phases. Here, by adjusting the particle size of MOF stationary phases from microscale to nanoscale, we successfully enhance the separation abilities of these "low-performance" MOFs. Three zirconium-based MOFs (NU-1000, PCN-608, and PCN-222) with different organic ligands were synthesized with sizes of tens of micrometers and hundreds of nanometers, respectively. All the nanoscale MOFs exhibited exceedingly higher separation abilities than the respective microscale MOFs. The mechanism investigation proved that reducing the particle size can reduce the mass transfer resistance, thus enhancing the column efficiency by controlling the separation kinetics. Modulating the particle size of MOFs is an efficient way to enhance the separation capability of "low-performance" MOFs and to design high-performance MOF stationary phases.

Linker Scissoring Strategy Enables Precise Shaping of Metal-Organic Frameworks for Chromatographic Separation.

Precise shaping of metal-organic frameworks (MOFs) is significant in both fundamental coordination chemistry and practical applications, such as catalysis, separation, and biomedicine. Herein, we demonstrated a linker scissoring strategy for precisely shaping MOFs through surface conformational pairing. In this strategy, the bidentate linkers which were designed according to the original tetratopic ligands and the coordination environment of MOF surfaces, were utilized as the covering agents. The shape of these covering agents and the surface conformation of metals onto MOFs restricted them to coordinate on specific MOF facets thus precisely controlling the shape of the MOFs. Different shapes of PCN-608 from nanoplate (PCN-NP) to nanorod (PCN-NR) have been targeted by adding different bidentate linkers. The universality of this strategy was demonstrated by controlling the shapes of the NU-MOFs from nanoplate to nanorod. This strategy provides a new guiding principle to synthesize MOF nanocrystals with controlled shapes.

Enhancing the enzymatic inhibition performance of Cu-based metal-organic frameworks by shortening the organic ligands.

Creating more exposed active sites on the metal-organic framework (MOF) surface is crucial for enhancing the recognition ability of MOF artificial receptors. Here, a copper-based MOF Cu(im)2 (im = imidazole) was utilized to act as an artificial receptor, inhibiting the activity of α-chymotrypsin. The shortest diazole ligand reduced the distance between regenerative copper sites, creating as many active sites as possible on the MOF unit surface. The amount of copper(ii) centers on the Cu(im)2 surface was calculated to be 4.96 × 106µm-2. Thus, Cu(im)2 showed exceedingly higher inhibition performance than other copper-based MOFs. The ChT activity was almost inhibited (88.8%) after the incubation with only 20 µg mL-1 Cu(im)2 for 10 min. The binding between ChT and Cu(im)2 was very fast with high affinity. Further results proved that Cu(im)2 inhibited the activity of ChT through electrostatic interactions and coordination interactions via the mixed inhibition mode. This strategy to use short ligands to create more active sites on the MOF surface provides a new direction to enhance the inhibition efficiency.

Controlling the Stacking Modes of Metal-Organic Framework Nanosheets through Host-Guest Noncovalent Interactions.

The tuning of metal-organic framework (MOF) nanosheet stacking modes from molecular level was rarely explored although it significantly affected the properties and applications of nanosheets. Here, the different stacking modes of Zr-1, 3, 5-(4-carboxylphenyl)-benzene framework nanosheets were synthesized through the induction of different host-guest noncovalent interactions. The solvents of methyl benzene and ethyl acetate induced twisted stacking of nanosheets with the specific rotation angles of 12°, 18°, 24° and 6°, 18°, 24°, 30°, respectively, which was in agreement with theoretical calculations. Meanwhile, the alkanes were likely to vertically enter the pores of Zr-BTB nanosheets because of steric hindrance and hydrophobic interactions, resulting in the untwisted stacking of nanosheets. The untwisted ordered nanopores showed the excellent gas chromatographic separations of benzene derivative isomers, which was better than twisted nanosheets stacking and commercial columns. This work uncovers a rational strategy to control the stacking of two-dimensional MOF nanosheets.

Precise Spatial-Designed Metal-Organic-Framework Nanosheets for Efficient Energy Transfer and Photocatalysis.

High-efficiency photocatalysis in metal-organic frameworks (MOF) and MOF nanosheets (NSs) are often limited by their short-lived charge separation as well as self-quenching. Here, we propose to use the energy-transfer process (EnT) to increase charge separation, thus enhancing the catalytic performance of a series of MOF NSs. With the use of NS, the photocatalyst can also be well isolated to reduce self-quenching. Tetrakis(4-carboxyphenyl) porphyrin (H4 TCPP) and 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4 TBAPy) linkers were chosen as the acceptor and donor moieties, respectively. Accounting for the precise spatial design afforded by the MOF NSs, the donor and acceptor moieties could be closely positioned on the NSs, allowing for an efficient EnT process as well as a high degree of site isolation. Two templates, donor-on-acceptor NS and acceptor-on-donor NS catalysts, were successfully synthesized, and the results show that the second one has much enhanced catalytic performances over the first one due to site-isolated active photocatalysts.

[Functional analysis of autism-associated NRXN1ß gene promoter].

Neurexins are neuron-specific synaptic proteins, and abnormal structure of Neurexin1ß is closely associated with autism. To characterize the minimal promoter of autism-associated NRXN1ß gene and identify functional elements regulating its transcription, luciferase reporter plasmids containing different regulatory regions upstream of NRXN1ß gene were constructed. After transfecting HEK293 cells with these plasmids, the minimal promoter region of NRXN1ß gene was determined by detecting the transcriptional activity of luciferase reporter genes while the corresponding functional elements that significantly enhance or inhibit the activity of reporter genes were further screened out. To identify cis-acting elements, continuous nucleotide mutation within the functional regions and adjacent DNA sequences were generated using site-directed mutagenesis techniques and then transcriptional regulatory elements in corresponding regions were analyzed using transcription factor binding prediction tool. Our results showed for the first time that the minimal promoter region of human NRXN1ß gene is located between positions -88 and +156 (-88/+156); two regions -88/-73 and +156/+149 enhance while the region +229/+419 inhibits promoter activity. The region -84/-63 significantly enhances promoter activity as cis-acting elements, suggesting the presence of DBP and ABF1 transcription factor binding sites in this region.

Polar alcohol guest molecules regulate the stacking modes of 2-D MOF nanosheets.

The modulation of two-dimensional metal-organic framework (2-D MOF) nanosheet stacking is an effective means to improve the properties and promote the application of nanosheets in various fields. Here, we employed a series of alcohol guest molecules (MeOH, EtOH and PrOH) to modulate Zr-BTB (BTB = benzene-1,3,5-tribenzoate) nanosheets and to generate untwisted stacking. The distribution of stacking angles was statistically analyzed from high-angle annular dark-field (HAADF) and fast Fourier transform (FFT) images. The ratios of untwisted stacking were calculated, such as 77.01% untwisted stacking for MeOH, 83.45% for EtOH, and 85.61% for PrOH. The obtained untwisted Zr-BTB showed good separation abilities for different substituted benzene isomers, superior para selectivity and excellent column stability and reusability. Control experiments of 2-D Zr-TCA (TCA = 4,4',4''-tricarboxytriphenylamine) and Zr-TATB (TATB = 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzoic acid) nanosheets with similar pore sizes and stronger polarity regulated by the alcohol guests exhibited moderate separation performance. The electron microscopy images revealed that polar alcohol regulation dominantly generated the twisted stacking of Zr-TCA and Zr-TATB with various Moiré patterns. Polar guest molecules, such as alcohols, provide strong host-guest interactions during the regulation of MOF nanosheet stacking, providing an opportunity to design new porous Moiré materials with application prospects.

[Rational design of high performance metal organic framework stationary phase for gas chromatography].

Metal organic frameworks (MOFs) are assembled from metal ions or clusters and organic ligands. The high tunability of these components offers a solid structural foundation for achieving efficient gas chromatography (GC) separation. This review demonstrates that the design of high performance MOFs with suitable stationarity should consider both the thermodynamic interactions provided by these MOFs and the kinetic diffusion of analytes. Thermodynamic parameters are basic indicators for describing the interactions between various analytes and the stationary phase. Thermodynamic parameters such as retention factors, McReynolds constants, enthalpy changes, and entropy changes can reflect the relative intensity of thermodynamic interactions. For example, a larger enthalpy change indicates a stronger thermodynamic interaction between the analytes and stationary phase, whereas a smaller enthalpy change indicates a weaker interaction. In addition, the degree of entropy change reflects the relative degrees of freedom of analytes in the stationary phase. A larger entropy change indicates that the analytes have fewer degrees of freedom in the stationary phase. The higher the degree of restriction, the closer the adsorption of the analytes and, thus, the longer the retention time. Thermodynamic interactions, such as metal affinity, π-π interactions, polarity, and chiral sites, can be rationally introduced into MOF structures by pre- or post-modifications depending on the target analytes. These tailored thermodynamic interactions create a favorable environment with subtle differences for efficient analyte separation. For example, MOF stationarity may require large conjugation centers to provide specific π-π interactions to separate benzenes. Chiral groups may be required in the MOF structure to provide sufficient interactions to separate chiral isomers. The kinetic diffusion rate of the analytes is another critical factor that affects the separation performance of MOFs. The diffusion coefficients of analytes in the stationary phase (Ds) can be used to evaluate their diffusion rates. The chromatographic dynamics equation illustrates that the chromatographic peak of analytes tends to be sharper and more symmetrical when the Ds is large, whereas a wider trailing peak may appear when the Ds is small. The Van Deemter equation also proves that a low Ds may lead to a high theoretical plate height and low column efficiency, whereas a high Ds may lead to a low theoretical plate height and increased column efficiency. Analyte diffusion can be significantly influenced by the pore size, shape, particle size, and packing mode of MOFs. For instance, an excessively small pore size results in increased mass transfer resistance, which affects the diffusion of analytes in the stationary phase, probably leading to serious peak trailing. Thus, a suitable pore size is required to enhance the kinetic diffusion of analytes and improve the separation performance of MOFs. Theoretically, the design of a high performance MOF stationary phase requires the creation of routes for the rapid diffusion of analytes. However, the separation ability of an MOF is determined by not only the kinetic diffusion rate of the analytes but also the thermodynamic interactions it provides. An excessively fast diffusion rate may lead to insufficient interactions between the analytes and MOFs, compromising their ability to effectively separate different analytes. The thermodynamic interactions and kinetic diffusion of analytes are synergistic and mutually essential. Therefore, this review concludes with research on the influence of both the thermodynamic interactions and kinetic diffusion of analytes on the performance of MOF stationary phases. Based on the findings of this review, we propose that high performance MOF stationary phases can be achieved by balancing the thermodynamic interactions and kinetic diffusion of analytes in these phases through the rational design of the MOF structure. We believe that this review provides useful guidelines for the design of high performance MOF stationary phases.

Gradual deterioration of fatty liver disease to liver cancer via inhibition of AMPK signaling pathways involved in energy-dependent disorders, cellular aging, and chronic inflammation.

Introduction: Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer kind. According to recent research, a fatty liver increases the risk of hepatocellular cancer. Nevertheless, the AMPK signaling pathway is crucial. In addition, 5'-AMP-activated protein kinase (AMPK) is strongly linked to alterations in the tumor microenvironment, such as inflammation, hypoxia, and aging. The objective of this study is to evaluate the impact of the AMPK signaling pathway on the progression of fatty liver to HCC. Methods: In this study, we established a mouse liver cancer model using high-fat diets and nano-nitrosamines (nano-DEN). In addition, we employed a transcriptomic technique to identify all mRNAs detected in liver samples at the 25th weekexpression of proteins linked with the LKB1-AMPK-mTOR signaling pathway, inflammation, aging, and hypoxia was studied in microarrays of liver cancer tissues from mice and humans. These proteins included p-AMPK, LKB1, mTOR, COX-2, ß-catenin, HMGB1, p16, and HIF-1α. Results: Data were collected at different times in the liver as well as in cancerous and paracancerous regions and analyzed by a multispectral imaging system. The results showed that most of the genes in the AMPK signaling pathway were downregulated. Prakk1 expression was upregulated compared to control group but downregulated in the cancerous regions compared to the paracancerous regions. Stk11 expression was downregulated in the cancerous regions. Mtor expression was upregulated in the cancerous regions. During liver cancer formation, deletion of LKB1 in the LKB1-AMPK-mTOR signaling pathway reduces phosphorylation of AMPK. It contributed to the upregulation of mTOR, which further led to the upregulation of HIF1α. In addition, the expression of ß-catenin, COX-2, and HMGB1 were upregulated, as well as the expression of p16 was downregulated. Discussion: These findings suggest that changes in the AMPK signaling pathway exacerbate the deterioration of disrupted energy metabolism, chronic inflammation, hypoxia, and cellular aging in the tumor microenvironment, promoting the development of fatty liver into liver cancer.

Anisotropic flexibility and rigidification in a TPE-based Zr-MOFs with scu topology.

Tetraphenylethylene (TPE)-based ligands are appealing for constructing metal-organic frameworks (MOFs) with new functions and responsiveness. Here, we report a non-interpenetrated TPE-based scu Zr-MOF with anisotropic flexibility, that is, Zr-TCPE (H4TCPE = 1,1,2,2-tetra(4-carboxylphenyl)ethylene), remaining two anisotropic pockets. The framework flexibility is further anisotropically rigidified by installing linkers individually at specific pockets. By individually installing dicarboxylic acid L1 or L2 at pocket A or B, the framework flexibility along the b-axis or c-axis is rigidified, and the intermolecular or intramolecular motions of organic ligands are restricted, respectively. Synergistically, with dual linker installation, the flexibility is completely rigidified with the restriction of ligand motion, resulting in MOFs with enhanced stability and improved separation ability. Furthermore, in situ observation of the flipping of the phenyl ring and its rigidification process is made by 2H solid-state NMR. The anisotropic rigidification of flexibility in scu Zr-MOFs guides the directional control of ligand motion for designing stimuli-responsive emitting or efficient separation materials.

Homogeneously Mixing Different Metal-Organic Framework Structures in Single Nanocrystals through Forming Solid Solutions.

Pore engineering plays a significant role in the applications of porous materials, especially in the area of separation and catalysis. Here, we demonstrated a metal-organic framework (MOF) solid solution (MOSS) strategy to homogeneously and controllably mix NU-1000 and NU-901 structures inside single MOF nanocrystals. The key for the homogeneous mixing and forming of MOSS was the bidentate modulator, which was designed to have a slightly longer distance between two carboxylate groups than the original tetratopic ligand. All of the MOSS nanocrystals showed a uniform pore size distribution with a well-tuned ratio of mesopores to micropores. Because of the appropriate pore ratio, MOSS nanocrystals can balance the thermodynamic interactions and kinetic diffusion of the substrates, thus showing exceedingly higher separation abilities and a unique elution sequence. Our work proposes a rational strategy to design mixed-porous MOFs with controlled pore ratios and provides a new direction to design homogeneously mixed MOFs with a high separation ability and unique separation selectivity.

Regulating metal-organic frameworks as stationary phases and absorbents for analytical separations.

Metal-organic frameworks (MOFs) are highly ordered framework systems composed of metal centers and organic linkers formed through coordination bonds. The diversity of metal elements and easily modified organic ligands, together with controllable synthetic approaches, gives rise to the designability of various MOF structures and topologies and the capability of MOFs to be functionalized. Their structural diversity provides MOFs with many unique properties, such as permanent porosity, flexible structures, thermostability, and high adsorption capacity, leading to great practicability in technical applications. In this review, we concentrate on the applications of MOFs in the field of gas chromatography, high-performance liquid chromatography, and the enrichment of biomolecules, based on rational arrangements in the structures and functions of MOFs. Moreover, we emphasize the importance of structural and chemical regulations for the improvement of separation efficiency.

Modulating the stacking modes of nanosized metal-organic frameworks by morphology engineering for isomer separation.

Modulating different stacking modes of nanoscale metal-organic frameworks (MOFs) introduces different properties and functionalities but remains a great challenge. Here, we describe a morphology engineering method to modulate the stacking modes of nanoscale NU-901. The nanoscale NU-901 is stacked through solvent removal after one-pot solvothermal synthesis, in which different morphologies from nanosheets (NS) to interpenetrated nanosheets (I-NS) and nanoparticles (NP) were obtained successfully. The stacked NU-901-NS, NU-901-I-NS, and NU-901-NP exhibited relatively aligned stacking, random stacking, and close packing, respectively. The three stacked nanoscale NU-901 exhibited different separation abilities and all showed better performance than bulk phase NU-901. Our work provides a new morphology engineering route for the modulation of the stacking modes of nano-sized MOFs and improves the separation abilities of MOFs.

Ultramicroporous metal-organic frameworks for capillary gas chromatographic separation.

Fine-tuning of the SiF62--containing metal-organic frameworks (SIFSIX) through the substitution of metal centers and ligands changed the apertures from 8.3 Å to 3.8 Å, resulting in ultramicropores and notably improving the separation performance of alkane isomers. Herein, we reported SIFSIX-1-Zn, SIFSIX-1-Cu and SIFSIX-3-Zn as representative stationary phases for capillary gas chromatography (GC). The capillary column coated with ultramicroporous SIFSIX-3-Zn efficiently separated the alkane isomers and benzene homologues, which outperformed SIFSIX-1-Zn and SIFSIX-1-Cu. This resulted from size matching between the window of the ultramicroporous SIFSIX-3-Zn and the analytes, which was also supported by McReynolds constants, column efficiency and peak tailing effect. It opened up a new avenue for ultramicroporous materials in the chromatography separation of isomers.

Discovery of precise pH-controlled biomimetic catalysts: defective zirconium metal-organic frameworks as alkaline phosphatase mimics.

The well-controlled structural motifs of zirconium metal-organic frameworks (Zr-MOFs) and their similarity to enzyme cofactors make them ideally suited for biomimetic catalysis. However, the activation methodologies for these motifs, the structural information about active conformations and the reaction mechanism during these biomimetic reactions, are largely unknown. Herein, we have explored the precise pH-controlled activation processes, active sites, and reaction mechanisms for a series of Zr-MOFs as alkaline phosphatase mimics. Activation of the Zr-MOFs with a broad range and precise changes of pH led to the discovery of the MOF-catalyzed volcano plot with activity versus pH changes. This unique response revealed the existence of the precisely pH-controlled active form of the material, which was confirmed with computational analysis using density functional theory and diffuse reflectance infrared Fourier transform spectroscopy. These results will open a window for state-of-the-art design of efficient MOF enzyme mimics in aqueous solution.